Piezoelectric signaling device

ABSTRACT

A gong-type signaling device having a pair of metal gongs, a clapper affixed to a clapper shaft which is in turn affixed to an elongate piezoelectric element activated by the application of an a.c. voltage. The device is provided with an adjustable loudness control including a pair of upright members, one disposed on each side of the clapper shaft and movable along the longitudinal axis thereof to restrict the velocity with which the clapper strikes the metal gongs to a preselected level thereby controlling the loudness of the signaling device.

v United States Patent Storz [151 3,671,958 [451 June 20,1972

[54] PIEZOELECTRIC SIGNALING DEVICE [72] Inventor: Frederick Storz, Englishtown, NJ.

73 Assignee: on: Automatic Electric Laboratories, In-

corporated, Northlake, 111.

[22] Filed: April29, 1971 [21] Appl.No.: 138,541

[52] U.S. C1. ...340/392, 84/407, 1 16/149 [51] Int. Cl. ..G10k 1/063 [58] Field of Search ..340/392, 403, 401 402;

[56] References Cited UNITED STATES PATENTS Pena .;...340/392 Whidden ..34o/392 3,500,393 3/1970 Roberton et a1. ..340/402 X Primary E.\'aminer.lohn W. Caldwell Assistant Examiner--William M. Wannisky Attorney-K. Mullerheim, B. E. Franz, Robert F. Van Epps and Theodore C. Jay, Jr.

[57 ABSTRACT A gong-type signalingdevice having apair of metal gongs, a clapper affixed to a clapper shaft which is in turn affixed to an elongate piezoelectric element activated by the application of an a.c. voltage. The device is provided with an adjustable loudness control including a pair of upright members, one disposed on each side of the clapper shaft and movable along the longitudinal axis thereof to restrict the velocity with which the clapper strikes the metal gongs to a preselected level thereby controlling the loudness of the signaling device.

7 Claims, 4 Drawing Figures PATENTEDJUHZO m2 SHEET 1 OF 2 FREDERICK G4 STORZ AGENT PATENTEDJUN 20 m2 SHEET 2 BF 2 PIEZOELECTRIC SIGNALING DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to the field of acoustic signaling devices and more particularly to a new and improved piezoelectric ringer having an adjustable loudness control.

2. Description of the Prior Art Prior to the present invention a gong-type ringer employing a piezoelectric transducer element was disclosed in US. Pat. No. 3,445,843 to P. J. Pena, entitled Piezoelectric Signaling Device" dated May 20, 1969. Although the device described therein was found to work satisfactorily, there remains a deficiency which becomes of significance, particularly in the application to ringers for telephone subsets, in that the disclosed device is of a fixed amplitude or loudness, i.e., the velocity with which the clapper strikes the metal gongs is fixed by the magnitude of the a.c. voltage applied to the piezoelectric transducer element. It is therefore desired to provide a mechanical loudness control whereby a user may manually adjust the volume of the signaling device.

It will be understood from the foregoing that among the various objects of the present invention are the following:

to provide a new and improved piezoelectric signaling device having an adjustable loudness control, and

to provide apparatus of the above-described character whereby loudness control is provided by purely mechanical means.

SUMMARY OF TFIE INVENTION The foregoing objectives of the present invention are accomplished by providing a base plate to one end of which a pair of metal gongs are mounted. A piezoelectric transducer element is clamped at the other end of the base plate and a clapper and clapper shaft assembly is affixed to the transducer such that when the transducer is activated by an a.c. voltage mechanical vibration is transmitted to the clapper which strikes the gongs. Loudness control is provided by a pair of upright members, one on each side of the clapper shaft, which are slidably mounted on the base plate such that the position of the upright members may be adjusted along the longitudinal axis of the clapper shaft. The kinetic energy of the vibrating clapper is partially absorbed by the upright members and the clapper shaft to a degree proportional to the distance at which the upright members are positioned with respect to the transducer clamp thereby limiting the velocity with which the clapper strikes the gongs and controlling the loudness of the device to the desired level. v

The foregoing as well as other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the various views of the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view of a piezoelectric signaling device having an adjustable mechanical loudness control in accordance with the present invention;

FIG. 2 is a side view of the device illustrated in FIG. 1;

FIG. 3 is an expanded view of the piezoelectric transducer element holder employed with the device illustrated in FIG. 1; and

FIG. 4 is an elevation view of an alternative embodiment of the mechanical loudness control element of the present invention.

I DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. I there is illustrated in elevation a piezoelectric signaling device having an adjustable mechanical loudness control in accordance with theprinciples of the present invention. The device includes a base plate to one end of which are affixed a pair of gongs l2 and 14. The

piezoelectric element 16 is clamped in a holder assembly 17 including first and second electrical contacts 18 held in position by insulating blocks 20 which are in turn mounted -in a mounting yoke 22. The transducer element holder assembly 17 provides the necessary clamping force, electrical terminations and adjustment features required by the piezoelectric element and will be more fully described hereinbelow. A clapper shaft 24 hearing a clapper 26 is affixed to the piezoelectric transducer element 16 by any convenient means, an epoxy cement, however, being preferred in the practice of this invention. An a.c. voltage applied to the transducer element 16" via electrical leads 28 and electrical contacts 18 cause the transducer element 16 tovibrate in the flexural mode such that the clapper 26 strikes the gangs 12 and 14.

The adjustable mechanical loudness control mechanism 30 in its simplest form comprises a pair of substantially rigid.

upright members 32 and 34 which may be mounted on or integrally formed with a slider element 36 which is in turn disposed in a channel 38 in the base plate 10 such that the position of the upright members 32 and 34 along the longitudinal axis of the clapper shaft 24 may be varied. When the upright members 32 and 34 are adjusted close to the clamping end of the clapper shaft 24 the shaft is allowed unrestricted movement therebetween and the clapper 26 strikes the metal gongs 12 and 14 at a maximum velocity thereby producing maximum loudness. As the upright members 32 and 34 are adjusted toward the clapper 26, vibration of the clapper shaft 24 becomes more restricted. Due to the kinetic energy in the vibrating clapper 26, the clapper shaft 24 tends to bend around the rigid upright members 32 and 34 to a degree determined by the stiffness of the clapper shaft 24. Under this condition the clapper shaft 24 acts as a spring in absorbing some of the kinetic energy from the clapper 26. This absorption of energy by the clapper shaft 24 and to a limited degree by the upright members 32 and 34 causes the clapper 26 to strike the gongs l2 and 14 at a lower velocity than when the clapper shaft is unrestricted. Thus the loudness of the device is readily increased or decreased by adjusting the position of the upright members 32 and 34 away from and toward the clapper respectively.

With reference now to FIG. 2 there is illustrated a side view of the apparatus of FIG. 1 wherein like elements are identified by like reference numerals and wherein the mechanical loudness control adjustment is more clearly shown.

In order that the mechanical loudness mechanism 30 be provided provided with a plurality of discrete loudness adjustment positions a series of grooves 40 are formed in the slider element 36 traverse to the longitudinal axis of the clapper shaft 24. A flat spring member 42 is fixed at one end to the base plate 10 and formed at its other end to mate with the grooves 40. The member 42 is biased to press against the slider element 36 and thereby lock into any selected one of the grooves 40. An adjustment tab 44 is attached-to or formed with the slider element 36 and extends through a slot (not shown) in the base plate 10. The position of the upright members 32 and 34 is thus adjusted by moving the adjustment tab 44 thereby providing simple and efficient loudness control of the signaling device.

FIG. 3 is an exploded view of the piezoelectric transducer element holder subassembly illustrated at 17 in the embodiment of FIG. 1. The transducer element 16 may be of any type which will provide the desired flexural vibration on the application of an a.c. voltage. A particular transducer element structure which is of utility in the practice of the present invention is of the lead zirconate-titanate type laminated with thin electrodes as described in US. Pat. No. 3,445,843 referenced hereinabove. As stated hereinabove the clapper shaft 24 is cemented to one end of the transducer element 16, the other end of which is clamped between first and second electrical contacts 18. The electrical contacts 18 are held in position by the insulating blocks 20 which are mounted in the mounting yoke 22 by set screws 46. The transducer element holder 22 may thus be mounted on the base plate 10 of the signaling device such that it is adjustable in rotation. With this transducer holder subassembly construction the piezoelectric transducer element 16, clapper shaft 24 and clapper 26 may conveniently be removed for replacement or repair without disturbing the electrical connections to the contacts 18 thereby eliminating the requirement for removal of the entire signaling assembly from any other device in which it may be mounted A provision for rotational adjustment of the mounting yoke 22 also facilitates the adjustment of the clapper 26 with respect to the metal gongs l2 and 14.

FIG. 4 illustrates in elevation an alternative embodiment of the mechanical loudness control mechanism having utility in the practice of this invention. Elements common to those described hereinabove again identified by like reference numerals. Although very similar in overall appearance and operation the embodiment illustrated in FIG. 4 involves the use of upright members formed of a spring tempered material. The upright members 32 and 34 are preferably formed in a single piece and provided with resilient pads 48 on the facing interior surfaces. It is preferred that the resilient pads 48 have curved surfaces to thereby provide a substantially point contact for the clapper shaft 24. In operation with the signaling device illustrated in FIG. 1 the spring tempered upright members 32 and 34 with their associated resilient pads 48 will move laterally when struck by the vibrating clapper shaft 24. The closer the upright members 32 and 34 are moved toward the clapper the greater will be their displacement when struck by the clapper shaft 24 and a proportionally greater amount of the kinetic energy in the clapper 26 will be absorbed. This increase in the absorbed energy by the spring tempered upright members 32 and 34 produces a decrease in the striking velocity of the clapper 26 and thereby provides a decrease in the loudness of the signaling device.

Adjustment of the loudness control mechanism illustrated in FIG. 4 may be substantially the same as described herein above with reference to FIG. 2. Alternatively any convenient threaded or lever means may be provided to adjust the position of the upright members along the longitudinal axis of the clapper shaft. From the foregoing it will be understood that the present invention provides an improved piezoelectric signaling device whereby the objectives set forth herein above are efficiently met. Since changes in the foregoing structure will occur to those skilled in the art without departure from the scope of the invention it is intended that all matter contained in the foregoing description or shown in the appended drawings shall be interpreted as illustrativeand not in a limiting sense.

Having described what is new and novel and desired to secure by Letters Patent, what is claimed is:

1. An improved piezoelectric signaling device comprising:

a base;

an elongate piezoelectric transducer element operative to vibrate in a planar flexural mode on the application of an alternating voltage;

means for clamping said transducer at one end thereof to said base;

a clapper shaft affixed at one end to the free end of said piezoelectric transducer element;

a clapper afiixed to said clapper shaft;

gong means mounted on said base adjacent said clapper;

coupling means through which an alternating voltage may be applied to said piezoelectric transducer element such that said clapper is driven to intermittently strike said gong means with a preselected maximum velocity;

a slider element slidably mounted on said base and adjustable along the longitudinal axis of said clapper shaft, and first and second upright members afiixed to said slider element, one disposed on each side of said clapper shaft normal to the plane of the flexural mode vibrations of said piezoelectric transducer element, and operative to restrict the vibratory motion of said clapper shaft and thereby restrict the velocity with which said clapper strikes said gong means to a selected level less than said maximum. 2. Apparatus as recited in claim 1 further including a plurality of parallel grooves disposed in the upper surface of said slider element transverse to the longitudinal axis of said clapper shaft, and

a flat spring member fixed at one end to said base, shaped at its other end to mate with a selected one of said grooves and biased to press said slider element against said base thereby providing a plurality of discrete loudness adjustment positions.

3. Apparatus as recited in claim 1 wherein said upright members are substantially rigid and integrally formed with said slider element.

4. Apparatus as recited in claim I wherein said upright members are formed of a spring tempered material and undergo lateral displacement when struck by said clapper shaft thereby partially absorbing kinetic energy from said clapper in proportion to the magnitude of the lateral displacement of said members.

5. Apparatus as recited in claim 4 further including first and second resilient pads, one disposed on the surface of each said upright member adjacent said clapper shaft, and having curved surfaces such that a substantially point contact is provided for said clapper shaft.

6. Apparatus as recited in claim 1 wherein said transducer clamping means comprises a mounting yoke adapted for mounting on said base;

first and second electrically insulating blocks disposed within said mounting yoke;

first and second electrical contacts disposed between said first and second insulating blocks and adapted to receive said transducer element;

means for applying pressure through said mounting yoke, said insulating blocks, and said electrical contacts to thereby clamp said transducer element therebetween; and

means for securing said mounting yoke to said base.

7. Apparatus as recited in claim 6 wherein said mounting yoke is adjustably secured to said base such as to be adjustable in rotation whereby the longitudinal axis of said transducer element may be adjusted with respect to said gong means.

, UNITED STATES PATENT OFFICE CERTIFICATE OF CORREMWN Patent No. 3 6.71 958 Dated June 20 1972 FREDERICK STORZ Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover page, line [73] after "Laboratories" delete (comma Signed and sealed this 17th day of April 1973.

. (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT SOTTSCHALK Attesting Officer 5 Commissloner of Patents FORM PO-1050 uscoMM-oc 60376-P69 U.S. GOVERNMENT FRINTING OFFICE l9! O-JGG-384 UNITED STATES PATENT OFFHIE' CERTIFMTE @F CQEQ'HQN Patent No. a 671 958 Dated June 20 1972 Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover page, line [73] after "Laboratories" delete (comma Signed and sealec] this 17th day of April 1973.

. (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT SOTTSCHALK Attesting Officer Commissioner of Patents F ORM PO-IOSO (10-69) USCOMM-DC 603764 69 a 0.5. GOVERNMENY PRINTING OFFICE: I969 o-aes-3a4 

1. An improved piezoelectric signaling device comprising: a base; an elongate piezoelectric transducer element operative to vibrate in a planar flexural mode on the application of an alternating voltage; means for clamping said transducer at one end thereof to said base; a clapper shaft affixed at one end to the free end of said piezoelectric transducer element; a clapper affixed to said clapper shaft; gong means mounted on said base adjacent said clapper; coupling means through which an alternating voltage may be applied to said piezoelectric transducer element such that said clapper is driven to intermittently strike said gong means with a preselected maximum velocity; a slider element slidably mounted on said base and adjustable along the longitudinal axis of said clapper shaft, and first and second upright members affixed to said slider element, one disposed on each side of said clapper shaft normal to the plane of the flexural mode vibrations of said piezoelectric transducer element, and operative to restrict the vibratory motion of said clapper shaft and thereby restrict the velocity with which said clapper strikes said gong means to a selected level less than said maximum.
 2. Apparatus as recited in claim 1 further including a plurality of parallel grooves disposed in the upper surface of said slider element transverse to the longitudinal axis of said clapper shaft, and a flat spring member fixed at one end to said base, shaped at its other end to mate with a selected one of said grooves and biased to press said slider element against said base thereby providing a plurality of discrete loudness adjustment positions.
 3. Apparatus as recited in claim 1 wherein said upright members are substantially rigid and integrally formed with said slider element.
 4. Apparatus as recited in claim 1 wherein said upright members are formed of a spring tempered material and undergo lateral displacement when struck by said clapper shaft thereby partially absorbing kinetic energy from said clapper in proportion to the magnitude of the lateral displacement of said members.
 5. Apparatus as recited in claim 4 further including first and second resilient pads, one disposed on the surface of each said upright member adjacent said clapper shaft, and having curved surfaces such that a substantially point contact is provided for said clapper shaft.
 6. Apparatus as recited in claim 1 wherein said transducer clamping means comprises a mounting yoke adapted for mounting on said base; first and second electrically insulating blocks disposed within said mounting yoke; first and second electrical contacts disposed between said first and second insulating blocks and adapted to receive said transducer element; means for applying pressure through said mounting yoke, said insulating blocks, and said electrical contacts to thereby clamp said transducer element therebetween; and means for securing said mounting yoke to said base.
 7. Apparatus as recited in claim 6 wherein said mounting yoke is adjustably secured to said base such as to be adjustable in rotation whereby the longitudinal axis of said transducer element may be adjusted with respect to said gong means. 